A streptavidin-cellulose-binding domain fusion protein that binds biotinylated proteins to cellulose.

A fusion protein, Sta-CBDCex, which comprises streptavidin with a cellulose-binding domain (CBDCex) fused to its C terminus, was produced in the cytoplasm of Escherichia coli, where it formed inclusion bodies. Renatured Sta-CBDCex, recovered from the inclusion bodies, adsorbed to Avicel, a microcrystalline cellulose. The cellulose-bound Sta-CBDCex in turn bound biotinylated alkaline phosphatase or biotinylated beta-glucosidase. The immobilized beta-glucosidase remained fully active during 2 weeks of continuous column operation at 50 degrees C.